1. Field of the Invention
The present invention relates generally to a technique for providing telephony control fault tolerance in a communications system, and more specifically, to such a technique that provides agent workstation telephony control fault tolerance.
2. Brief Description of Related Prior Art
Systems for managing and routing calls through public and/or private communications networks are known in the art. Conventional automatic call distribution (ACD) systems route calls to agents in telemarketing and service inquiry centers, and provide limited real-time call management and reporting capabilities. A typical ACD system will monitor the status of the agent and, when an incoming call is received, selects the agent to handle a particular service request. Reporting and performance data from the agents are also generated by the ACD.
One particular type of scheme for distributing calls to agents is disclosed in Frauenthal et al., U.S. Pat. No. 4,737,983. According to Frauenthal et al., data representing the present call congestion of each of the ACD systems is accumulated in a data base. Using the data in the data base, the percentage of calls made to the ACD systems, as a group, is determined. The information is then used to generate call routing information. When a new call is made to the central office, the routing information is queried to determine which of the ACD systems is to receive the call, so as to balance the call traffic load across the ACD systems.
Another call management and distribution scheme is provided in Gechter et al., U.S. Pat. No. 5,036,535. This patent discloses a system for automatically distributing telephone calls placed over a network to one of a plurality of agent stations connected to the network via service interfaces, and providing status messages to the network. Gechter et al.'s disclosed system includes means for receiving the agent status messages and call arrival messages from the network, which means are connected via a network service interface to the network. Routing means responsive to the receiving means is provided for generating a routing signal provided to the network to connect the incoming call to an agent station through the network. In the system disclosed in Gechter et al., when an incoming call is made to the call router, it decides which agent station should receive the call, establishes a call with that agent station, and then transfers the original call onto the second call to connect the incoming caller directly to the agent station and then drops out of the connection (See, Gechter et al., column 11, lines 45–51).
Other prior art call management, routing, and distribution techniques are disclosed in Andrews et al., U.S. Pat. No. 5,878,130 issued Mar. 2, 1999, which is assigned to the Assignee of the subject application. This patent discloses a communications system and method for automatically making telephone routing decisions with global authority based upon information gathered in real time from the entire communications system and global optimization criteria. The entirety of the disclosure of the Andrews et al. patent is incorporated herein by reference.
Conventional communications systems of the type disclosed in the aforesaid Andrews et al. patent typically comprise one or more ACD systems connected to each other via at least one public switched telephone network (PSTN). The ACD systems and the PSTN may be controlled by a central controller so as to route calls to and from agents (and/or caller services, such as interactive voice response units) associated with such systems, and callers external thereto, through the ACD systems and PSTN.
Unfortunately, conventional ACD systems typically are complex telecommunications devices that are costly to acquire and maintain. Thus, the use of conventional ACD systems in a communications system inherently increases the cost and complexity of implementing, using, and maintaining the communications system.
Accordingly, in an effort to reduce or eliminate the need to use such conventional ACD systems, it has been proposed to provide non-ACD agent systems that exhibit ACD-like functionality and operation in a communication system. In such non-ACD agent systems, a plurality of agent computer-telephony integration (CTI) workstation computer nodes may be provisioned with controllable telephony devices. These telephony devices may be directly connected to the PSTN, or alternatively, may be connected to the PSTN via a PBX to enable certain call operations (e.g., agent conference and consultative call operations, and call transfer operations) to be implemented in the non-ACD agent system. Further alternatively, the telephony devices may be configured to establish and receive Internet Protocol (IP) telephony calls, using voice-over-IP technology, over an IP network. This may offer cost advantages over traditional Plain Old Telephone Service (POTS) telephony, as in contradistinction to POTS telephony, both voice and data may be carried over a single IP network connection; the use of IP telephony has also become more attractive with the widespread and increasing availability of broadband access. The agent workstations, their telephony devices, and the PBX may be controlled by a telephony control mechanism external to the workstations.
More specifically, the control mechanism may comprise at least one telephony control process residing and executing in at least one computer node linked to the workstations via computer network links. This control process controls other telephony control processes (e.g., server processes based upon the telephony application interface (TAPI) protocol of Microsoft Corporation of Redmond, Wash.) resident in the workstations. The TAPI server processes in the workstations control the respective telephony devices in the workstations so as to facilitate implementation of desired call operations.
As is known to those skilled in the art, according to the TAPI protocol, a single respective client process can control only a single respective TAPI server process. Thus, in order to implement the above-described non-ACD agent system, in each agent workstation, a respective TAPI-based client process may be provided to act as a respective interface that permits the establishment of a respective control communication path or link between the telephony control process in the external telephony control mechanism and the respective TAPI server process resident in the workstation. By providing these respective TAPI-based client processes, it becomes possible for the telephony control process in the external telephony control mechanism to control the multiple TAPI server processes in the workstations, and thereby, to control the telephony operations of workstations' telephony devices.
There are a number of ways in which a control communication link between the telephony control process in the external telephony control mechanism and a TAPI-based client process may fail (i.e., experience a failure condition in its operation, such as, ceasing to permit exchange of telephony commands and responses thereto). Examples of events that may cause such a control communication link to fail include the failure of the client process, the failure of the external telephony control process or mechanism, and/or the failure of a network communication link between the workstation and the mechanism. A failure of the client process or the external telephony control process can be caused by, e.g., the experiencing by such processes of an untrapped exception or a deadlock in execution. A failure of a network link or the external telephony control mechanism can be caused by, e.g., a fatal electrical or mechanical failure of the network link or mechanism.
Unfortunately, if the control communication path established by a TAPI-based client process in an agent workstation fails, then it becomes impossible to control the telephony operations of the workstation's telephony device; this can make it impossible for the agent associated with the workstation to properly receive, establish, and process calls using the workstation.